[ adding lkml, dropping 'ndctl prefix ]
On Thu, Jun 1, 2017 at 10:39 PM, Dan Williams <dan.j.williams@xxxxxxxxx> wrote:
> The inode destruction path for the 'dax' device filesystem incorrectly
> assumes that the inode was initialized through 'alloc_dax()'. However,
> if someone attempts to directly mount the dax filesystem with 'mount -t
> dax dax mnt' that will bypass 'alloc_dax()' and the following failure
> signatures may occur as a result:
>
> kill_dax() must be called before final iput()
> WARNING: CPU: 2 PID: 1188 at drivers/dax/super.c:243 dax_destroy_inode+0x48/0x50
> RIP: 0010:dax_destroy_inode+0x48/0x50
> Call Trace:
> destroy_inode+0x3b/0x60
> evict+0x139/0x1c0
> iput+0x1f9/0x2d0
> dentry_unlink_inode+0xc3/0x160
> __dentry_kill+0xcf/0x180
> ? dput+0x37/0x3b0
> dput+0x3a3/0x3b0
> do_one_tree+0x36/0x40
> shrink_dcache_for_umount+0x2d/0x90
> generic_shutdown_super+0x1f/0x120
> kill_anon_super+0x12/0x20
> deactivate_locked_super+0x43/0x70
> deactivate_super+0x4e/0x60
>
> general protection fault: 0000 [#1] SMP DEBUG_PAGEALLOC
> RIP: 0010:kfree+0x6d/0x290
> Call Trace:
> <IRQ>
> dax_i_callback+0x22/0x60
> ? dax_destroy_inode+0x50/0x50
> rcu_process_callbacks+0x298/0x740
>
> ida_remove called for id=0 which is not allocated.
> WARNING: CPU: 0 PID: 0 at lib/idr.c:383 ida_remove+0x110/0x120
> [..]
> Call Trace:
> <IRQ>
> ida_simple_remove+0x2b/0x50
> ? dax_destroy_inode+0x50/0x50
> dax_i_callback+0x3c/0x60
> rcu_process_callbacks+0x298/0x740
>
> Add missing initialization of the 'struct dax_device' and inode so that
> the destruction path does not kfree() or ida_simple_remove()
> uninitialized data.
>
> Cc: <stable@xxxxxxxxxxxxxxx>
> Fixes: 7b6be8444e0f ("dax: refactor dax-fs into a generic provider of 'struct dax_device' instances")
> Reported-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
> ---
> drivers/dax/super.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/dax/super.c b/drivers/dax/super.c
> index 6ed32aac8bbe..922d0823f8ec 100644
> --- a/drivers/dax/super.c
> +++ b/drivers/dax/super.c
> @@ -210,9 +210,12 @@ EXPORT_SYMBOL_GPL(kill_dax);
> static struct inode *dax_alloc_inode(struct super_block *sb)
> {
> struct dax_device *dax_dev;
> + struct inode *inode;
>
> dax_dev = kmem_cache_alloc(dax_cache, GFP_KERNEL);
> - return &dax_dev->inode;
> + inode = &dax_dev->inode;
> + inode->i_rdev = 0;
> + return inode;
> }
>
> static struct dax_device *to_dax_dev(struct inode *inode)
> @@ -227,7 +230,8 @@ static void dax_i_callback(struct rcu_head *head)
>
> kfree(dax_dev->host);
> dax_dev->host = NULL;
> - ida_simple_remove(&dax_minor_ida, MINOR(inode->i_rdev));
> + if (inode->i_rdev)
> + ida_simple_remove(&dax_minor_ida, MINOR(inode->i_rdev));
> kmem_cache_free(dax_cache, dax_dev);
> }
>
> @@ -423,6 +427,7 @@ static void init_once(void *_dax_dev)
> struct dax_device *dax_dev = _dax_dev;
> struct inode *inode = &dax_dev->inode;
>
> + memset(dax_dev, 0, sizeof(*dax_dev));
> inode_init_once(inode);
> }
>
>